Refine layernorm naming and test code (#497)

* Sync the naming

* Sync the test of layernorm with groupnorm

* Sync the naming

* Minor change for comment and log

* [What] Add saveMean and SaveInvVariance in the interface.
[Why] These can optimize the backward

[ROCm/composable_kernel commit: d4d1147f0a]

example/27_layernorm/layernorm_blockwise.cpp

@@ -100,6 +100,8 @@ int main()
         gamma_dev.GetDeviceBuffer(),
         beta_dev.GetDeviceBuffer(),
         y_dev.GetDeviceBuffer(),
+        nullptr,
+        nullptr,
         PassThrough{});
 
     if(!device_instance.IsSupportedArgument(argument_ptr.get()))

example/42_groupnorm/groupnorm_sigmoid_fp16.cpp

@@ -128,6 +128,8 @@ int main(int argc, char* argv[])
         gamma_dev.GetDeviceBuffer(),
         beta_dev.GetDeviceBuffer(),
         y_dev.GetDeviceBuffer(),
+        nullptr,
+        nullptr,
         y_element_op);
 
     if(!device_instance.IsSupportedArgument(argument_ptr.get()))